Method for determining relative amount of oxygen containing gas in a gas mixture

• US 5,288,375 A
• Filed: 06/19/1992
• Issued: 02/22/1994
• Est. Priority Date: 09/30/1988
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Motor Company
• Inventors: Soltis, Richard E., Logothetis, Eleftherios M.
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US07/901,315
• Time in Patent Office: 613 Days
• Field of Search: 204/153.22, 204/153.18, 204/421-429
• US Class Current: 205/784
• CPC Class Codes: G01N 27/417 using cells , i.e. more than one cell and probes with solid electrolytes

Abstract

The electrochemical device and method measures the relative amount of a measurement gas consisting essentially of at least one oxygen containing gas in a gas mixture containing at least a second oxygen containing gas which is capable of being pumped out or disassociated at a voltage less than that which is capable of disassociating the measurement gas. The mixture may comprise, e.g., O₂, CO₂, and H₂ O. Two electrochemical pump cells and a support structure form a restricted volume in communication through an aperture to the gas mixture. The device comprises a first external electrical circuit means across a first pump cell for applying a voltage to cause molecules of substantially all second oxygen containing gas molecules inside the restricted volume to be pumped out from the restricted volume or disassociated. The device also comprises a second external electrical circuit means across a second pump cell causes for applying a voltage to disassociate only of substantially all measurement gas molecules inside the volume. The device further comprises a third external electrical circuit means to measure the current flowing in the second pump cell, this current being proportional to the relative amount of measurement gas in the gas mixture. The invention also is directed to a planar electrochemical device and method for measuring the relative percentage of a measure gas in a gas mixture like that described above.

Claims

1. A method employing an electrochemical oxygen pumping device for measuring the relative amount of a measurement gas consisting essentially of at least one oxygen containing gas in a gas mixture comprising in addition at least a second oxygen containing gas which is capable of being pumped out of said device or disassociated at a voltage less than that which is capable of disassociating said measurement gas, said method comprising the steps of:

providing communication between said gas mixture and a first porous layer of an electrochemical device, which device comprises;

a generally planar first electrochemical oxygen pump cell including a relatively dense platelet with one of a pair of porous electrodes on each of two spaced sides of said platelet, one of said porous electrodes being exposed;

the first porous layer deposited on one of the electrodes of said first pump cell;

a generally planar second electrochemical oxygen pump cell including a first porous electrode, a second porous layer and a second porous electrode deposited successively on said first porous layer;

applying and maintaining a first voltage across said second pump cell to positively bias said second electrode (i) sufficiently to cause substantially all said second oxygen containing gas molecules inside said first porous layer to be pumped out or disassociated by a current flowing through said second pump cell and (ii) insufficiently to disassociate said measurement gas;

applying and maintaining simultaneously with the maintaining of said first voltage, a second voltage across said first pump cell to positively bias the exposed electrode of said first pump cell sufficiently to disassociate only substantially all of said measurement gas molecules inside said first porous layer; and

measuring said current flowing through said first pump cell, said current being proportional to the relative amount of said measurement gas in said gas mixture.

2. A method as recited in claim 1, which further comprises measuring said current flowing through said second pump cell, said second pump cell current being proportional to the relative amount of said second oxygen containing gas in said gas mixture.

3. The method as recited in claim 1, further comprising the step of continuously measuring said current flowing through said first pump cell for continuously monitoring said measurement gas in said gas mixture while said first and second applied voltages are maintained.

4. The method as recited in claim 1, further comprising the steps of changing said first and second voltages applied to said first and second pump cells, respectively, for allowing the measurement of a different measurement gas.